<?php
/**
 * ==============================================================================
 * SAQEL ENTERPRISE - STUDENT ACCESS CONTROL & GRADE PROGRESSION SERVICE
 * ==============================================================================
 * 
 * ملف: StudentAccessControlService.php
 * الهدف المعماري:
 * 1. حوكمة وصول الطالب للمحتوى بناءً على صفه الدراسي الحالي والمترفع له حصراً بواسطة الرقم الوطني.
 *    - إذا كان الطالب في الصف السادس، يُمنع تماماً من الوصول لحصص الصف الخامس (السابق) أو الصف السابع (اللاحق).
 * 2. تطبيق النموذج المالي المزدوج:
 *    - طلبة المدارس الشريكة (مديرية الثقافة العسكرية أو المدارس الخاصة المسجلة): الوصول مجاني تماماً (0 دينار)
 *      عبر تصريح مدرسي مشمول (school_included).
 *    - الطلبة الخارجيون المستقلون: يلزمهم تصريح مدفوع عبر كليك (full_marketplace).
 * 3. الترفيع السنوي الآلي (Annual Grade Promotion) وقفل السجلات القديمة.
 */

namespace App\Services;

use App\Core\Database;
use App\Core\Security;

class StudentAccessControlService
{
    /**
     * التحقق الصارم من أهلية وصلاحية الطالب للوصول إلى درس معين
     * 
     * @param int|null    $studentId   معرف الطالب في قاعدة البيانات
     * @param string|null $nationalId  الرقم الوطني الأردني
     * @param string      $targetGrade الصف الدراسي للدرس المطلوب (مثل grade_6, grade_10)
     * @param int|null    $courseId    معرف الدورة
     * @param int|null    $lessonId    معرف الدرس
     * @return array [allowed => bool, reason => string, student_grade => string, is_sponsored => bool]
     */
    public static function validateLessonAccess(
        ?int $studentId,
        ?string $nationalId,
        string $targetGrade,
        ?int $courseId = null,
        ?int $lessonId = null,
        bool $allowSideEffects = false
    ): array {
        // 1. استرجاع بيانات الطالب وسجله الدراسي
        $student = null;
        if ($studentId) {
            $student = Database::selectOne(
                "SELECT s.*, sch.name as school_name, sch.type as school_type, sch.directorate_id,
                        d.type as directorate_type
                 FROM students s
                 LEFT JOIN schools sch ON s.school_id = sch.id
                 LEFT JOIN directorates d ON sch.directorate_id = d.id
                 WHERE s.id = ? LIMIT 1",
                [$studentId]
            );
        } elseif (!empty($nationalId)) {
            $student = Database::selectOne(
                "SELECT s.*, sch.name as school_name, sch.type as school_type, sch.directorate_id,
                        d.type as directorate_type
                 FROM students s
                 LEFT JOIN schools sch ON s.school_id = sch.id
                 LEFT JOIN directorates d ON sch.directorate_id = d.id
                 WHERE s.national_id = ? LIMIT 1",
                [$nationalId]
            );
        }

        // Protected content requires a current student record. A preview flag
        // must not turn a missing/deleted student into a valid entitlement.
        if (!$student) {
            return [
                'allowed'       => false,
                'reason'        => 'unauthenticated_or_not_found',
                'message'       => 'يرجى تسجيل الدخول أو إدخال الرقم الوطني للتحقق من الصلاحية الدراسية.',
                'student_grade' => 'unknown',
                'is_sponsored'  => false
            ];
        }

        $activeStudentGrade = self::normalizeGrade((string)($student['grade_level'] ?? ''));
        $normalizedTargetGrade = self::normalizeGrade($targetGrade);
        if ($activeStudentGrade !== $normalizedTargetGrade) {
            return [
                'allowed' => false, 'reason' => 'grade_mismatch',
                'message' => 'الدرس خارج صف الطالب المسجل؛ غيّر صفك من الملف المصرح أو راجع المدرسة.',
                'student_grade' => $activeStudentGrade, 'target_grade' => $normalizedTargetGrade,
                'is_sponsored' => (bool)($student['is_school_sponsored'] ?? false),
            ];
        }

        // A lesson read never changes grade or creates a school access pass.
        // Entitlements are checked against an actual course and school roster.
        if ($courseId) {
            $course = Database::selectOne(
                'SELECT c.id, c.school_id, c.is_school_exclusive, c.is_published, c.price_jod,
                        c.grade_level, t.is_school_exclusive AS teacher_school_exclusive,
                        t.is_marketplace_public
                 FROM courses c JOIN teachers t ON t.id=c.teacher_id WHERE c.id=? LIMIT 1',
                [$courseId]
            );
            if (!$course || (int)$course['is_published'] !== 1) {
                return ['allowed' => false, 'reason' => 'course_unavailable', 'student_grade' => $activeStudentGrade];
            }
            if ($course['grade_level'] !== null && $course['grade_level'] !== ''
                && self::normalizeGrade((string)$course['grade_level']) !== $normalizedTargetGrade) {
                return ['allowed' => false, 'reason' => 'course_grade_mismatch', 'student_grade' => $activeStudentGrade];
            }
            if ($lessonId) {
                $sourceLesson = Database::selectOne('SELECT course_id FROM lessons WHERE id=? LIMIT 1', [$lessonId]);
                if (!$sourceLesson || (int)$sourceLesson['course_id'] !== $courseId) {
                    return ['allowed' => false, 'reason' => 'lesson_course_mismatch', 'student_grade' => $activeStudentGrade];
                }
            }

            $schoolId = (int)($course['school_id'] ?? 0);
            if ($schoolId > 0 || (int)$course['is_school_exclusive'] === 1 || (int)$course['teacher_school_exclusive'] === 1) {
                if ($schoolId <= 0 || (int)($student['school_id'] ?? 0) !== $schoolId
                    || empty($student['is_school_sponsored'])) {
                    return ['allowed' => false, 'reason' => 'school_scope_mismatch', 'student_grade' => $activeStudentGrade];
                }
                $roster = Database::selectOne(
                    'SELECT grade_level FROM school_rosters WHERE school_id=? AND claimed_student_id=? AND is_claimed=1 LIMIT 1',
                    [$schoolId, (int)$student['id']]
                );
                if (!$roster || self::normalizeGrade((string)$roster['grade_level']) !== $normalizedTargetGrade) {
                    return ['allowed' => false, 'reason' => 'school_roster_unverified', 'student_grade' => $activeStudentGrade];
                }
                return [
                    'allowed' => true, 'reason' => 'school_course_included',
                    'student_grade' => $activeStudentGrade, 'is_sponsored' => true,
                ];
            }

            if ((int)$course['is_marketplace_public'] !== 1) {
                return ['allowed' => false, 'reason' => 'not_marketplace_public', 'student_grade' => $activeStudentGrade];
            }
            if ((float)$course['price_jod'] <= 0.0) {
                return ['allowed' => true, 'reason' => 'free_course', 'student_grade' => $activeStudentGrade, 'is_sponsored' => false];
            }

            $activePass = Database::selectOne(
                "SELECT id, pass_type, expires_at, is_active FROM course_access_passes 
                 WHERE student_id = ? AND course_id = ? AND is_active = 1
                   AND pass_type IN ('discounted_micro_pass','full_marketplace')
                   AND (expires_at IS NULL OR expires_at > NOW())
                 LIMIT 1",
                [(int)$student['id'], $courseId]
            );

            if ($activePass) {
                return [
                    'allowed'       => true,
                    'reason'        => 'paid_pass_active',
                    'student_grade' => $activeStudentGrade,
                    'is_sponsored'  => false,
                    'pass_id'       => $activePass['id']
                ];
            }

            // An explicit free preview is allowed only on a public course.
            if ($lessonId) {
                $lesson = Database::selectOne("SELECT is_free_preview FROM lessons WHERE id = ? LIMIT 1", [$lessonId]);
                if ($lesson && !empty($lesson['is_free_preview'])) {
                    return [
                        'allowed'       => true,
                        'reason'        => 'free_preview',
                        'student_grade' => $activeStudentGrade,
                        'is_sponsored'  => false
                    ];
                }
            }

            return [
                'allowed'       => false,
                'reason'        => 'payment_required',
                'message'       => 'يتطلب هذا المساق تفعيل الاشتراك عبر نظام الدفع الفوري (CliQ) للطلبة المستقلين خارج المدارس الشريكة.',
                'student_grade' => $activeStudentGrade,
                'is_sponsored'  => false,
                'course_id'     => $courseId
            ];
        }

        // افتراضياً لدروس المنهاج المعتمد لنفس الصف
        return [
            'allowed'       => true,
            'reason'        => 'curriculum_default',
            'student_grade' => $activeStudentGrade,
            'is_sponsored'  => false
        ];
    }

    /**
     * ترفيع الطالب سنوياً إلى الصف اللاحق (مثال: من خامس إلى سادس)
     * وإلغاء صلاحية الوصول لحصص الصفوف السابقة
     */
    public static function promoteStudent(int $studentId, string $newGradeLevel): array
    {
        $student = Database::selectOne("SELECT id, full_name, grade_level, national_id FROM students WHERE id = ? LIMIT 1", [$studentId]);
        if (!$student) {
            return ['status' => 'error', 'message' => 'الطالب غير موجود'];
        }

        $oldGrade = self::normalizeGrade($student['grade_level']);
        $promotedGrade = self::normalizeGrade($newGradeLevel);

        Database::query("UPDATE students SET grade_level = ?, updated_at = NOW() WHERE id = ?", [$promotedGrade, $studentId]);

        Database::query("UPDATE school_rosters SET grade_level = ? WHERE national_id = ?", [$promotedGrade, $student['national_id']]);

        // إلغاء تفعيل التصاريح السابقة الخاصة بالصف المنتهي
        Database::query(
            "UPDATE course_access_passes cap
             JOIN courses c ON cap.course_id = c.id
             SET cap.is_active = 0
             WHERE cap.student_id = ? AND c.grade_level = ?",
            [$studentId, $oldGrade]
        );

        $oldName = self::getGradeDisplayName($oldGrade);
        $newName = self::getGradeDisplayName($promotedGrade);

        return [
            'status'         => 'success',
            'student_id'     => $studentId,
            'student_name'   => $student['full_name'],
            'old_grade'      => $oldGrade,
            'promoted_grade' => $promotedGrade,
            'message'        => "تم ترفيع الطالب ({$student['full_name']}) بنجاح من ({$oldName}) إلى ({$newName}) وتحديث الصلاحيات."
        ];
    }

    /**
     * ترفيع كشف المدرسة بالكامل دفعة واحدة (Batch Grade Promotion)
     */
    public static function batchPromoteRoster(int $schoolId, string $fromGrade, string $toGrade): array
    {
        $from = self::normalizeGrade($fromGrade);
        $to   = self::normalizeGrade($toGrade);

        $count = (int)Database::selectOne(
            "SELECT COUNT(*) as cnt FROM students WHERE school_id = ? AND grade_level = ?",
            [$schoolId, $from]
        )['cnt'];

        Database::query(
            "UPDATE students SET grade_level = ?, updated_at = NOW() WHERE school_id = ? AND grade_level = ?",
            [$to, $schoolId, $from]
        );

        Database::query(
            "UPDATE school_rosters SET grade_level = ? WHERE school_id = ? AND grade_level = ?",
            [$to, $schoolId, $from]
        );

        return [
            'status'          => 'success',
            'school_id'       => $schoolId,
            'from_grade'      => $from,
            'to_grade'        => $to,
            'promoted_count'  => $count,
            'message'         => "تم ترفيع {$count} طالباً في المدرسة بنجاح وتحديث صلاحياتهم الأكاديمية."
        ];
    }

    /**
     * توحيد أسماء ومفاتيح الصفوف
     */
    public static function normalizeGrade(string $grade): string
    {
        $g = strtolower(trim($grade));
        if (str_contains($g, 'عاشر') || str_contains($g, 'grade_10') || str_contains($g, 'grade10') || str_contains($g, 'grade 10') || $g === '10') return 'grade_10';
        if (str_contains($g, 'تاسع') || str_contains($g, 'grade_9') || str_contains($g, 'grade9') || str_contains($g, 'grade 9') || $g === '9') return 'grade_9';
        if (str_contains($g, 'ثامن') || str_contains($g, 'grade_8') || str_contains($g, 'grade8') || str_contains($g, 'grade 8') || $g === '8') return 'grade_8';
        if (str_contains($g, 'سابع') || str_contains($g, 'grade_7') || str_contains($g, 'grade7') || str_contains($g, 'grade 7') || $g === '7') return 'grade_7';
        if (str_contains($g, 'سادس') || str_contains($g, 'grade_6') || str_contains($g, 'grade6') || str_contains($g, 'grade 6') || $g === '6') return 'grade_6';
        if (str_contains($g, 'خامس') || str_contains($g, 'grade_5') || str_contains($g, 'grade5') || str_contains($g, 'grade 5') || $g === '5') return 'grade_5';
        if (str_contains($g, 'حادي') || str_contains($g, 'أول ثانوي') || str_contains($g, 'grade_11') || str_contains($g, 'grade 11') || $g === '11') return 'grade_11';
        if (str_contains($g, 'ثاني عشر') || str_contains($g, 'توجيهي') || str_contains($g, 'tawjihi') || str_contains($g, 'grade_12') || str_contains($g, 'grade 12') || $g === '12') return 'grade_12';
        return $g;
    }

    /**
     * اسم العرض للصف بالعربية
     */
    public static function getGradeDisplayName(string $gradeKey): string
    {
        return match ($gradeKey) {
            'grade_5'  => 'الصف الخامس الأساسي',
            'grade_6'  => 'الصف السادس الأساسي',
            'grade_7'  => 'الصف السابع الأساسي',
            'grade_8'  => 'الصف الثامن الأساسي',
            'grade_9'  => 'الصف التاسع الأساسي',
            'grade_10' => 'الصف العاشر الأساسي',
            'grade_11' => 'الصف الحادي عشر (الأول ثانوي)',
            'grade_12', 'tawjihi_2008' => 'الصف الثاني عشر (التوجيهي الوزاري)',
            default    => $gradeKey,
        };
    }
}